CRYSTALLINE STYLE OF LAMELLIBRANCHS 63 



and he demonstrated the action of the amylolytic ferments 

 present. 



Mitra ('01), with no review of the Uterature save the theories 

 given in the text-books of Gegenbaur, Balfour, and Glaus and 

 Sedgwick, repeated the work done by Barrios, Coupin, and some 

 others, and concluded that the style was a mass of enzyme, in 

 the nature of a globulin. Apparently he did not know of the 

 existence of the gastric shield. His conclusions wdll be con- 

 sidered in some detail in the discussion of this paper. 



Von Fiirth ('03) followed Mitra, but beheved it more reason- 

 able to suppose as did Coupin ('00), that the style was a mass of 

 mucus saturated with diastases, rather than a solid mass of 

 enzyme. Matthias ('14), whose work has already been consid- 

 ered, admitted the conclusions of Mitra. Allen ('14), accept- 

 ing the conclusions of Mitra in the main, showed that the forma- 

 tion and dissolution of the style are dependent wholly or in 

 part on the feeding activities. 



In addition to the above authors may be listed the following, 

 whose work is of less importance: 



Selenka ('68), in the description of the anatomy of Trigonia, 

 notes the presence of the style, lying in a blind sac opening into 

 the stomach. Egger ('87) describes the appearance of the style 

 with its co-axial layers in Jouannetia cumingii. Grobben ('92) 

 gives an account of the nature of the cilia of the intestine and of 

 the style sac. Mention of the style is made by Moquin-Tandon 

 ('85) in the Unionidae, and by Blanchard ('61) in the Pholadidae. 



Other investigators and their conclusions, not listed here, 

 will be considered in their appropriate connection in the main 

 body of the present paper. 



EXPERIMENTAL 



Materials and methods 



The investigations reported in this paper were carried on in the 

 Zoological Laboratory of the University of Wisconsin, and at the 

 floating laboratory of the New Jersey Agricultural Station for 

 research in oyster culture, on the coast of New Jersey. The 



